RT3

Question 1

viral agents that cause infectious pharyngitis (strep throat)

Answer 1

Rhinovirus
Adenovirus
Coronavirus

Question 2

bacterial agents that cause infectious pharyngitis (strep throat)

Answer 2

Strep pyogenes (usuallyGroupA β‐Strep) 
Corynebacterium diphtheriae

Question 3

signs and symptoms of strep throat/infectious pharyngitis

Answer 3

• Throat pain
• Difficulty swallowing
• Red and swollen tonsils, sometimes with white patches or streaks of pus
• Tiny red spots on the soft or hard palate — the area at the back of the roof of the mouth
• Swollen, tender lymph glands (nodes) in the neck
• Fever
• Headache
• Rash
• Stomachache and sometimes vomiting, especially in younger children
• Fatigue

Question 4

why must you test specifically for strep throat to diagnose it

Answer 4

one can have all the signs and symptoms and not have a true strep throat infection – more likely to get these symptoms from a viral infection or less likely from other illnesses

Question 5

can you tell by looking into the mouth if the cause of an infectious pharyngitis is bacterial or viral

Answer 5

no you cannot tell by looking so one must do a point of care test to be sure

Question 6

viral agents that cause bronchiolitis

Answer 6

Adenovirus
Influenza Virus
Respiratory Syncitial Virus

think AIR through the bronchioles

Question 7

bacterial agents that cause bronchiolitis

Answer 7

Bordetella pertussis

Mycoplasma pneumonia

Question 8

what are the assays used for the microbial agents of bronchiolitis

Answer 8

you do a swab to use the assay

for the viral AIR agents
Adenovirus: PCR, antigen detection
Influenza virus: virus isolation
Respiratory syncitial virus: antigen detection

for the bacterial agents
bordatella pertussis: culture, DFA, serology, PCR
mycoplasma pneumonia: acid fast, culture

Question 9

respiratory bacteria by definition have what type of oxygen requirements

Answer 9

aerobes and facultative anaerobes

Question 10

how do you culture media for respiratory bacteria

Answer 10

get a routine sputum specimen and you can use either a blood, chocolate, or macconkeys agar

Question 11

significance of using chocolate and mcconkey agar

Answer 11

chocolate agar - blood agar that has been heated to break open RBCs and release their content

mcconkeys: for selection and differentiation

Question 12

what pathogens required special growth media that is not standard and what agar do they use

Answer 12

bordatella pertussis: bordet- gengou

c. diphtheria: tinsdale agar

Question 13

characteristic of streptococci

Answer 13

small, gram positive, cocci in shape, metabolized through fermentation with lactic acid production, facultative anaerobe (but actually have all the qualities of aerotolerant anaerobe - grow in presence of oxygen, metabolize via fermentation, have only superoxide dismutase)

Question 14

clinical syndrome of streptococci pyogenes

Answer 14

pharyngitis (strep throat)

Question 15

describe the name streptococci pyogenes

Answer 15

Group A streptococcus according to Lancefield classification

pyogenes = induce of pus formation due to leukocidin production (leukocidin destroys leukocytes which will make pus)

Question 16

how are streptococci classified

Answer 16

based on 16s rRNA sequencing

Question 17

streptococci are classified by groups based on

Answer 17

polysaccharides (major cell wall carbs)

there’s group A –> W though there is no I or J

Question 18

example of streptococci that does not have a carb group

Answer 18

S. pnuemonia

Question 19

lab identifications of streptococci

Answer 19

• 􏰀Gram Positive Spheres in chains (Older cultures become Gram Variable)
• 􏰀Lack catalase (facultative anaerobes)
• 􏰀Growth enhanced by CO2
• 􏰀Nutritionally fastidious (􏰀Normal culture medium = Blood agar (BA) 􏰀Yeast extract + peptone +5% blood)

Question 20

streptococcal have large amounts of virulence factors which is not all expressed by all strain. what determines this variability?

Answer 20

transduction mediated gene transfer or transformation

Question 21

describe s. pyogenes on blood agar

Answer 21

• where there is production of streptolysin S, there is beta hemolysis (tot destruction of erythrocytes) making the plate transparent
• sensitive to bacitrain so no growth where this antibiotic is present

Question 22

clinical syndrome of corynebacterium diphtheria

Answer 22

severe pharyngitis (diphtheria)

Question 23

physical features of corynebacterium diphtheria

Answer 23

gram positive, club shaped, nonsporeforming rods that are pleomorphic with chinese letter arrangement

Question 24

what does corynebacterium diphtheria looks like on a gram stain

Answer 24

purple
irregular in shape
rod shaped
one end is thicker than the other

Question 25

why is corynebacterium diphtheria unusual in developed countries

Answer 25

because of DPT vaccine -- the D component is diphtheria toxoid

Question 26

where are endemics and outbreaks of diphtheria seen

Answer 26

endemics - subtropical and tropical areas | outbreak - places with breakdown in health infrastructure

Question 27

pathogenesis of corynebacterium diphtheria

Answer 27

organism is non invasive and does not enter the bloodstream but the toxin that it releases enters the blood stream and invades tissues organism grows in a biofilm on the surface of the pharynx while its necrotizing toxin kills the tissue that it gets to

Question 28

main virulence factor of diphtheria

Answer 28

the diphtheria exotoxin

Question 29

how are the genes for diphtheria toxin acquired

Answer 29

via lysogenic conversion

Question 30

complication of diphtheria

Answer 30

pharyngitis can be so severe that it blocks the airway --> suffocation bull neck, pseudomembranous

Question 31

what three tests can be done to see if you grew diphtheria toxin on the blood agar aka testing for toxigenicity

Answer 31

Elek, EIA, PCR

Question 32

Elek, EIA, PCR -- which is more effective and which is more probable (cheaper to use)

Answer 32

more effective - PCR | Elek test is cheaper, quicker, simpler

Question 33

explain what positive elek test would look like

Answer 33

beneath the filter paper that has the antitoxin, there will be lines of precipitin (at angles) indicating presence of diphtheria toxin

Question 34

viral agents of infectious sinusitis and otitis media

Answer 34

Rhinovirus Adenovirus Coronavirus

Question 35

if you see viral agent in an infectious sinusitis and otitis media, what type of infection is it mostly

Answer 35

it is mostly an exogenous infection

Question 36

bacterial agent of infectious sinusitis and otitis media

Answer 36

``` Streptococcus pneumoniae Haemophilus influenzae (part of normal flora) ```

Question 37

if you see bacterial agent in infectious sinusitis and otitis media, what type of infection is it mostly

Answer 37

it is mostly an endogenous infection

Question 38

clinical syndromes of haemophilus influenzae

Answer 38

otitis media, pneumonia, epiglottis

Question 39

what is haemophilus influenzae the most common cause of

Answer 39

swelling of epiglottis and supraglottic tissue

Question 40

describe physical features of haemophilus influenzae

Answer 40

gram negative, pleomorphic, facultative anaerobe, normal component of normal flora, IgA proteases

Question 41

does h. influenza cause influenza

Answer 41

no

Question 42

pathogenesis of h. influenzae

Answer 42

it is gram neg bacteria so it has LPS which impairs ciliary function it has a pili also has a non-pilus adhesins --> P-2 outer membrane protein; attaches to sialic acid-containing mucin oligosaccharides

Question 43

what is the h. influenzae antiphagocytic capsule composed of

Answer 43

Polyribose Ribitol Phosphate (PRP)

Question 44

how do you culture and diagnose h. influenzae

Answer 44

catalase: positive coagulase: negative culture with chocolate agar with X and V growth factors

Question 45

what do the X and V factor do

Answer 45

``` X = acts as hemin V = acts as NAD ```

Question 46

what other haemophilus require both X and V factor

Answer 46

none just h. influenza